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<head><meta charset="utf-8"><title>ui diff between stable/beta and nightly · t-release · Zulip Chat Archive</title></head>
<h2>Stream: <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/index.html">t-release</a></h2>
<h3>Topic: <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html">ui diff between stable/beta and nightly</a></h3>

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<a name="241776747"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241776747" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241776747">(Jun 07 2021 at 13:34)</a>:</h4>
<p>well</p>



<a name="241776813"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241776813" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241776813">(Jun 07 2021 at 13:35)</a>:</h4>
<p>I guess it's finally time to figure out why the diagnostics change between beta and nightly if we ever want to land the builder checking nightly as stable :/</p>



<a name="241776814"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241776814" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241776814">(Jun 07 2021 at 13:35)</a>:</h4>
<p><a href="https://github.com/rust-lang/rust/pull/86098#issuecomment-855926670">https://github.com/rust-lang/rust/pull/86098#issuecomment-855926670</a></p>



<a name="241788451"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241788451" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241788451">(Jun 07 2021 at 14:53)</a>:</h4>
<p>ok I kinda figured out why that failure is happening</p>



<a name="241788570"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241788570" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241788570">(Jun 07 2021 at 14:54)</a>:</h4>
<p>the custom proc macro we have relies on <code>proc_macro2</code>, whose behavior around spans changes if you're running on nightly</p>



<a name="241788741"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241788741" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241788741">(Jun 07 2021 at 14:55)</a>:</h4>
<p><code>#[derive(SessionDiagnostic)]</code> is only used within the compiler though</p>



<a name="241788986"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241788986" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241788986">(Jun 07 2021 at 14:56)</a>:</h4>
<p>the options I see are:</p>
<ol>
<li>regress <code>SessionDiagnostic</code>'s own diagnostics by replicating stable's behavior on nightly</li>
<li>figure out a way to coerce <code>proc_macro2</code> to use nightly features on stable</li>
<li>implement <code>// only-nightly</code> in compiletest to ignore that test</li>
</ol>



<a name="241789019"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789019" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789019">(Jun 07 2021 at 14:57)</a>:</h4>
<p>since we're talking about an internal thing only I'm tempted to go with <a href="https://github.com/rust-lang/rust/issues/3">#3</a></p>



<a name="241789051"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789051" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789051">(Jun 07 2021 at 14:57)</a>:</h4>
<p><span class="user-mention" data-user-id="116122">@simulacrum</span> thoughts?</p>



<a name="241789109"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789109" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789109">(Jun 07 2021 at 14:57)</a>:</h4>
<p>gah</p>



<a name="241789130"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789130" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789130">(Jun 07 2021 at 14:57)</a>:</h4>
<p>that's a pain</p>



<a name="241789163"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789163" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789163">(Jun 07 2021 at 14:57)</a>:</h4>
<p>yeah, I think 3 is best in this case</p>



<a name="241789233"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789233" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789233">(Jun 07 2021 at 14:58)</a>:</h4>
<p>it really should be using cfg(accessible) or something, but oh well</p>



<a name="241789245"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789245" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789245">(Jun 07 2021 at 14:58)</a>:</h4>
<p>that's not a thing yet</p>



<a name="241789262"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789262" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789262">(Jun 07 2021 at 14:58)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116122">simulacrum</span> <a href="#narrow/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly/near/241789130">said</a>:</p>
<blockquote>
<p>that's a pain</p>
</blockquote>
<p>you're not wrong :)</p>



<a name="241789280"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789280" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789280">(Jun 07 2021 at 14:58)</a>:</h4>
<p><span class="user-mention silent" data-user-id="116122">simulacrum</span> <a href="#narrow/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly/near/241789163">said</a>:</p>
<blockquote>
<p>yeah, I think 3 is best in this case</p>
</blockquote>
<p><span aria-label="thumbs up" class="emoji emoji-1f44d" role="img" title="thumbs up">:thumbs_up:</span> will update the PR soon!</p>



<a name="241789745"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789745" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789745">(Jun 07 2021 at 15:01)</a>:</h4>
<p><span class="user-mention" data-user-id="121055">@Pietro Albini</span> fwiw it's also possible the right option is to get RUSTC_BOOTSTRAP added as a flag here - <a href="https://github.com/alexcrichton/proc-macro2/blob/master/build.rs#L119">https://github.com/alexcrichton/proc-macro2/blob/master/build.rs#L119</a></p>



<a name="241789772"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789772" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789772">(Jun 07 2021 at 15:01)</a>:</h4>
<p>but that's a bit neither here nor there</p>



<a name="241789808"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789808" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789808">(Jun 07 2021 at 15:01)</a>:</h4>
<p>realistically detecting nightly/dev is rarely what folks actually want :/</p>



<a name="241789999"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241789999" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241789999">(Jun 07 2021 at 15:02)</a>:</h4>
<p><em>personally</em> I'd like to have less RUSTC_BOOTSTRAP around <a href="http://crates.io">crates.io</a></p>



<a name="241790055"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241790055" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241790055">(Jun 07 2021 at 15:03)</a>:</h4>
<p>but I can try seeing if adding the env variable there fixes stuff</p>



<a name="241790315"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241790315" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241790315">(Jun 07 2021 at 15:05)</a>:</h4>
<p>oh, I mean, the ideal is that folks aren't doing nightly detection</p>



<a name="241790381"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241790381" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241790381">(Jun 07 2021 at 15:05)</a>:</h4>
<p>probably we should get cargo to expose a is-unstable cfg or something</p>



<a name="241790405"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241790405" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> simulacrum <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241790405">(Jun 07 2021 at 15:05)</a>:</h4>
<p>or at least, it might be a good idea</p>



<a name="241797972"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241797972" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> XAMPPRocky <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241797972">(Jun 07 2021 at 15:52)</a>:</h4>
<p><span class="user-mention silent" data-user-id="121055">Pietro Albini</span> <a href="#narrow/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly/near/241788986">said</a>:</p>
<blockquote>
<p>the options I see are:</p>
<ol>
<li>regress <code>SessionDiagnostic</code>'s own diagnostics by replicating stable's behavior on nightly</li>
<li>figure out a way to coerce <code>proc_macro2</code> to use nightly features on stable</li>
<li>implement <code>// only-nightly</code> in compiletest to ignore that test</li>
</ol>
</blockquote>
<p>Is the opposite of 2 possible? E.g. have <code>proc-macro2</code> behave the same on nightly as it does on stable?</p>



<a name="241798386"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241798386" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> bjorn3 <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241798386">(Jun 07 2021 at 15:55)</a>:</h4>
<p>That is option 1 I think.</p>



<a name="241798987"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241798987" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> XAMPPRocky <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241798987">(Jun 07 2021 at 15:59)</a>:</h4>
<p>Ah I thought that was a different route.</p>



<a name="241804661"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241804661" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241804661">(Jun 07 2021 at 16:39)</a>:</h4>
<p>well, adding the builder was useful <span aria-label="sweat smile" class="emoji emoji-1f605" role="img" title="sweat smile">:sweat_smile:</span></p>



<a name="241804663"></a>
<h4><a href="https://rust-lang.zulipchat.com#narrow/stream/241545-t-release/topic/ui%20diff%20between%20stable/beta%20and%20nightly/near/241804663" class="zl"><img src="https://rust-lang.github.io/zulip_archive/assets/img/zulip.svg" alt="view this post on Zulip" style="width:20px;height:20px;"></a> Pietro Albini <a href="https://rust-lang.github.io/zulip_archive/stream/241545-t-release/topic/ui.20diff.20between.20stable.2Fbeta.20and.20nightly.html#241804663">(Jun 07 2021 at 16:39)</a>:</h4>
<p><a href="https://github.com/rust-lang/rust/pull/86098#issuecomment-856088303">https://github.com/rust-lang/rust/pull/86098#issuecomment-856088303</a></p>



<hr><p>Last updated: Aug 07 2021 at 22:04 UTC</p>
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